Evangelos Ch. Tsirogiannis | Aristotle University of Thessaloniki (original) (raw)

Thesis Chapters by Evangelos Ch. Tsirogiannis

The increasing demand for robotized productions in the industrial sector entails the need for imp... more The increasing demand for robotized productions in the industrial sector entails the need for improvement of the robotic arms’ structures. The major criteria for the development of robot arm links are the stiffness and strength enhancement subject to mass reduction as well as cost and time elimination. Towards this direction, this work indicates an integrated methodology of developing robotic arm links considering the design and manufacturing concurrently. This methodology is implemented by lightweight strategies in conjunction with design for additive manufacturing (DFAM) methods. Initially, the Stäubli RX90BL robot arm case study is chosen and reverse engineering methodologies are applied in order to discover the design information of the robot arm links. Alongside, a new strategy for the three-dimensional design reconstruction is introduced, which is named ReCAD. In turn, the redesign of the robotic arm geometry is obtained by using the Solidworks and the Catia V5 software packages. Thereupon, the additive manufacturing (AM) technology is chosen for the production of the robot arm’s links. Actually, AM offers design freedom by means of DFAM methods and tools subject to DFAM constraints. Thereafter, the robot forearm link is redesigned to be manufactured by means of the selective laser sintering (SLS) additive manufacturing technology. SLS process could create cost effective industrial robot arm structures by using the powder processing technology. Advanced powder alloys based on aluminium imply low weight to stiffness and weight to strength ratio. Accordingly, the SIMP method of topology optimization is utilized in order to obtain the optimum design of the robotic arm. Considering the topology optimization capabilities, constraints and restrictions for AM the resulted robot forearm structure meets the requirements which were possessed in the development specifications. Actually, the proposed methodology is evaluated by weight reduction of the forearm design while the strength and stiffness retained the same. The breakthrough in this work is the development methodology of an industrial robot arm link via the SIMP topology optimization method in conjunction with the metal additive manufacturing technology subject to the design for SLS additive manufacturing capabilities and constraints.

The design of an urban car's chassis for the “Shell Eco Marathon” competition takes into account ... more The design of an urban car's chassis for the “Shell Eco Marathon” competition takes into account many performance parameters referring to the usage and the type of the vehi-cle and a variety of different constraints such as the overall weight, strength, stiffness and cost. In order to meet these demands, the chassis must be easily manufacturable and affordable. Towards this direction, a new design approach of a lightweight carbon fiber monocoque chassis, for an electric urban car, is proposed, which conforms to struc-tural, aesthetic, and ergonomic requirements. Initially, a new chassis design of an environmentally friendly, urban vehicle is presented, and based on that, a lighter and stronger innovative design approach is suggested. For the development of this innovative approach and during the conceptual design phase, the parametric design method was chosen, in order for the design to be modified easily. Additionally, the chassis high efficiency was obtained by following appropriate steps, rules and techniques which conform to the vehicle structural and dynamical constraints. These methods combined with the choice of carbon fiber, as a construction material, achieved the minimization of the overall chassis mass, maximizing strength perform-ance. The mechanical properties of a composite material such as the carbon fiber were also calculated during the design process. Furthermore, for academic and research purposes, a model that automatically calculates the total loads that are applied on a vehicle’s chassis, was created. The equations that were used to implement this model are derived from the theory of Vehicle Dynamics and are explained thoroughly. In order to validate the derived model, data such as track width, wheelbase, center of gravity, mass, et cetera were used as inputs. At the same time, a worst case stress scenario was chosen and the model's output was evaluated for the new, as well as the previous chassis design. The first step of a finite element analysis (FEA) method was performed by the pre-processor ANSA, a software of BETA CAE Systems, in order to evaluate the resistance of these two chassis designs, under this extreme stress scenario and to simulate them with the ANSYS solver. However, the ANSYS simulation was outside of the scope of this thesis. Finally, the manufacturing methods which are utilized to construct the carbon fiber monocoque chassis, are also explained.

Papers by Evangelos Ch. Tsirogiannis

Evangelos Ch. Tsirogiannis, Evangelos Daskalakis, Christos Vogiatzis, Foivos Psarommatis, Paulo Bartolo, Advanced composite armor protection systems for military vehicles: Design methodology, ballistic testing, and comparison, Composites Science and Technology, Volume 251, 2024, 110486, 2024

This study presents a new methodology for designing, manufacturing, and testing advanced armor pr... more This study presents a new methodology for designing, manufacturing, and testing advanced armor protection systems and applied to the development of three different protection solutions suitable for real armored vehicles. The backplate laminates of the presented composite armor protection solutions were composed of three different materials: steel, aluminum AA6082, and aluminum alloy AA2024 reinforced by multi-walled carbon nanotubes (MWCNTs). The frontal laminates remained the same for the three cases. Keeping almost the same mass while changing the material of each backplate and adapting the thickness, the three different protection systems were ballistically tested and compared according to Level 4 (Level IV) of the standard AEP-STANAG 4569 (projectile 14.5 mm × 114 mm API B32) with real military tests. Furthermore, the performance of the total laminated structure and the performance of each backplate in the total laminated structure were compared in terms of deformation and ballistic fractures. High-quality images acquired by the high-speed camera were helpful in evaluating and comparing the backplates and the entire protection system. The results show that all three protection configurations present high performance mechanical properties and ballistic characteristics compared to commonly used armor systems. Even the under-developed AA2024-CNTs composite is a promising near-term backplate solution.

Ballistic design and testing of a composite armour reinforced by CNTs suitable for armoured vehicles, Apr 26, 2023

This paper is investigating the use of composite armour reinforced by nanomaterials, for the prot... more This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured (LAV) and medium armoured military vehicles (MAV), and the interaction between the composite materials and high-performance ballistic projectiles. Four armour materials, consisted of front hybrid fibre reinforced polymer cover layer, ceramic strike-face, fibre reinforced polymer intermediate layer and the metal matrix composite reinforced backplate, were manufactured and assembled by adhesive technology. The proposed laminated protection system is suitable for armoured ground vehicles; however, it could be used as armour on ground, air and naval platforms. The design of the protection system, including material selection and thickness, was elaborated depending on the performance requirements of Level 4 ＋ STANAG 4569 military standard (projectile 14.5 mm x 114 mm API B32) and especially on a design philosophy which is analysed with the specifications. The backplate of this new composite is a hybrid material of Metal Matrix Composite (MMC) reinforced with carbon nanotubes (CNTs), manufactured with the use of powder metallurgy technique. The composite backplate material was morphologically, mechanically and chemically analysed. Results show that all plates are presenting high mechanical properties and ballistic characteristics, compared to commonly used armour plates. Real military ballistic tests according to AEP-STANAG 4569 were carried out for the total composite armour systems. After the ballistic tests, AA2024-CNT3 showed the best protection results, compared with the other plates (AA2024-CNT1 and AA2024-CNT2), with the projectile being unable to fully penetrate the composite plate.

Stergioudi, F.; Prospathopoulos, A.; Farazas, A.; Tsirogiannis, E.C.; Michailidis, N. Mechanical Properties of AA2024 Aluminum/MWCNTs Nanocomposites Produced Using Different Powder Metallurgy Methods. Metals 2022, 12, 1315. https://doi.org/10.3390/met12081315, 2022

Metal matrix composites are a class of materials with high potential for industrial application d... more Metal matrix composites are a class of materials with high potential for industrial application due to the multifaceted properties that they possess. In the present research, mechanical alloying via ball milling was used to produce AA2024 powder that was subsequently reinforced with multiwalled carbon nanotubes (MWCNTs). Dispersion of the MWCNTs in the AA2024 matrix was achieved also by ball milling. Two different powder metallurgy sequencies, (i) double pressing double sintering and (ii) hot pressing were used for compaction and consolidation of the AA2024 reinforced by MWCNTs. The produced nanocomposites outperform the pristine AA2024 in terms of compressive strength, elongation to failure, and microhardness. The strengthening mechanism was associated with the homogeneous distribution of MWCNTs in the AA2024 matrix and their efficient interfacial bonding, which was attested also by microstructural characterization. Hot pressing resulted in higher mechanical properties of the nanocomposite material. However, when reinforcement content was above 2 wt.% a dramatic decrease of mechanical properties was observed, attributed to clustering and inhomogeneous dispersion of the MWCNTs. The homogeneous dispersion of MWCNTs in the AA2024 matrix and the retaining of their structural integrity are pivotal in increasing the mechanical properties, which can be directly associated with the efficient interfacial load transfer between MWCNTs and AA2024 matrix.

Tsirogiannis, E.C., Stavroulakis, G.E. and Makridis, S.S. (2019) ‘Optimised ultrafast lightweight design and finite element modelling of a CFRP monocoque electric car chassis’, Int. J. Electric and Hybrid Vehicles, Vol. 11, No. 3, pp.255–287., Jul 26, 2019

A breakthrough in the process method has been developed by combined considerations in the demands... more A breakthrough in the process method has been developed by combined considerations in the demands of "Shell Eco Marathon" using finite element modelling (FEM). Ultrafast calculations have revealed novel chassis development. The most critical factors in designing the new chassis are the reduction of the weight, the improvement of strength and stiffness, the reduction of material and the manufacturing cost. The simple structural surfaces (SSS) method was used for an electric car so as the type of loading conditions which are applied to the chassis structure to be predicted. Afterwards, a new design approach for a lightweight carbon-fibre reinforced polymer (CFRP) monocoque chassis is proposed which conforms to structural, ergonomic, safety and aesthetic requirements. The SSS method in conjunction with the creation of the chassis load calculator (CLC) model and both the specialised and integrated methodology of the processing procedure through FEM, have attained the overcoming of the time consuming conceptual design process.

REDESIGN AND TOPOLOGY OPTIMIZATION OF AN INDUSTRIAL ROBOT LINK FOR ADDITIVE MANUFACTURING Evangelos Tsirogiannis, George-Christopher Vosniakos, Facta Universitatis, Series: Mechanical Engineering, Vol. 17, Issue 3, pp. 415-424, Feb 2, 2019

Design optimization for Additive Manufacturing is demonstrated by the example of an industrial ro... more Design optimization for Additive Manufacturing is demonstrated by the example of an industrial robot link. The part is first redesigned so that its shape details are compatible with the requirements of the Selective Laser Sintering technique. Subsequently, the SIMP method of topology optimization is utilized on commercially available software in order to obtain the optimum design of the part with restrictions applicable to Additive Manufacturing, namely member thickness, symmetry and avoidance of cavities and undercuts. Mass and strain energy are the design responses. The volume was constrained by a fraction of the initial mass. The desired minimization of maximum strain energy is expressed as an objective function. A 7% reduction in the mass of the part was achieved while its strength and stiffness remained unchanged. The process is supported by topology optimization software but it also involves some trial-and-error depending on the designer's experience.

Tsirogiannis, E.C.; Stavroulakis, G.E.; Makridis, S.S. Electric Car Chassis for Shell Eco Marathon Competition: Design, Modelling and Finite Element Analysis. World Electr. Veh. J. 2019, 10, 8., Jan 31, 2019

The increasing demand for energy efficient electric cars, in the automotive sector, entails the n... more The increasing demand for energy efficient electric cars, in the automotive sector, entails the need for improvement of their structures, especially the chassis, because of its multifaceted role on the vehicle dynamic behaviour. The major criteria for the development of electric car chassis are the stiffness and strength enhancement subject to mass reduction as well as cost and time elimination. Towards this direction, this work indicates an integrated methodology of developing an electric car chassis considering the modeling and simulation concurrently. The chassis has been designed in compliance with the regulations of Shell Eco Marathon competition. This methodology is implemented both by the use of our chassis load calculator (CLC) model, which automatically calculates the total loads applied on the vehicle’s chassis and by the determination of a worst case stress scenario. Under this extreme stress scenario, the model’s output was evaluated for the chassis design and the FEA method was performed by the pre-processor ANSA and the solver Ansys. This method could be characterized as an accurate ultrafast and cost-efficient method.

Tsirogiannis, E.C.; Siasos, G.I.; Stavroulakis, G.E.; Makridis, S.S. Lightweight Design and Welding Manufacturing of a Hydrogen Fuel Cell Powered Car’s Chassis. Challenges 2018, 9, 25, May 27, 2018

The development of the chassis for the hydrogen fuel cell powered car has been involved in the de... more The development of the chassis for the hydrogen fuel cell powered car has been involved in the designing and manufacturing aspects, while taking into consideration the mass, strength, stiffness, centre of gravity (COG), and manufacturing cost requirements. Towards this direction, a chassis design is proposed employing a space frame structure and constructed by an aluminium alloy with great strength. The structural design has been derived through the lightweight engineering approaches in conjunction with the part consolidation, Design for Assembly (DFA) and Design for Manufacture methods. Moreover, it has been performed in compliance with the safety regulations of the Shell Eco Marathon racing competition. The material's principal characteristics are the great strength, the low mass, as well as the great workability, machinability, and weldability. Following the national and global environmental issues, the recyclable characteristics of the aluminium alloy are an extra asset. Furthermore, the existence of aluminium alloy manufacturers around the fabricating area provides low cost supply and fast delivery benefits. The integration of the fuel cell powered vehicle is obtained through the designing and the manufacturing processes of the chassis and the parts fitted on the chassis. The manufacturing procedures are described thoroughly; mainly consisting of the cutting and welding processes and the assembling of the parts that are fitted on the chassis. Additionally, the proper welding parameters for the custom chassis design are investigated and are selected after deductive reasoning. The quality control of the weld joints is conducted by non-destructive methods (NDT) ensuring the required structural properties of the welds. A combination of the selected material, the specific type of the chassis, and the manufacturing processes lead to construction simplicity in a low manufacturing cost by using the existing laboratory equipment. Furthermore, the designing and manufacturing parameters lead to a stiff with a low centre of gravity, and the most lightweight chassis of the urban concept category at the Shell Eco Marathon race.

Evangelos Ch. Tsirogiannis, Georgios E. Stavroulakis, Sofoklis S. Makridis (2017) Design and Modelling Methodologies of an Efficient and Lightweight Carbon-fiber Reinforced Epoxy Monocoque Chassis, Suitable for an Electric Car. Mater. Sci. Eng. Adv. Res 2(1): 5-12., Feb 20, 2017

The design of an electric urban car's chassis for the "Shell Eco Marathon "competition takes into... more The design of an electric urban car's chassis for the "Shell Eco Marathon "competition takes into account the usage and the type of the vehicle. The most critical factors of designing the new chassis are: the reduction of the weight, improvement of strength and stiffness and reduction of material and manufacturing cost. Towards this direction, a new design approach for a lightweight carbon-fiber reinforced epoxy (CFRE) monocoque chassis, is proposed, which conforms to structural, ergonomic and aesthetic requirements. For the development of this innovative approach, the parametric design method was chosen, in order for the design to be modified easily. The chassis efficiency, in terms of high strength in low mass, was obtained by following appropriate design steps and rules which conform to the vehicle structural and dynamical constraints and by choosing the composite material CFRE. Additionally, a method that calculates the mechanical properties of the composite material CFRE is presented. Furthermore, a model has been created, which calculates automatically the total loads applied on the vehicle's chassis. Worst case stress scenario was chosen and the model's output was evaluated for the new chassis design.

Conference Presentations by Evangelos Ch. Tsirogiannis

Τα κτίρια απαιτούν την πρόσδοση θερμότητας μέσω θερμικών ή ψυκτικών μέσων με σκοπό την θέρμανση ή... more Τα κτίρια απαιτούν την πρόσδοση θερμότητας μέσω θερμικών ή ψυκτικών μέσων με σκοπό την θέρμανση ή ψύξη των χώρων τους ανάλογα με τις θερμικές απαιτήσεις τους. Οι θερμικές απαιτήσεις τους σχετίζονται εκτός των άλλων και από το βαθμό θερμικής μόνωσής τους, δηλαδή τον όγκο και τον τύπο τοποθετημένου θερμομονωτικού υλικού. Πετυχαίνοντας υψηλότερα επίπεδα μόνωσης σε ένα κτίριο, αυτό συντελεί σε λιγότερη ανάγκη για θέρμανση ή ψύξη το οποίο σημαίνει λιγότερο κατακεφαλήν κόστος θέρμανσης ή ψύξης καθώς και σε λιγότερους ρύπους το οποίο συνεπάγεται προστασία του περιβάλλοντος. Στην παρούσα εργασία διερευνούνται τα χρησιμοποιούμενα μονωτικά υλικά με βάση τα περιβαντολλογικά, τα τεχνικά και τα υγειονομικά χαρακτηριστικά τους. Αναφερόμενοι στα τεχνικά χαρακτητιστικά των μονωτικών υλικών, λαμβάνουμε υπόψιν μας χαρακτηριστικά όπως η θερμική απόδοση και η πυκνότητά τους, στα περιβαντολλογικά χαρακτηριστικά το βαθμό φιλικότητάς τους προς το περιβάλλον και το βαθμό ανακυκλωσιμότητάς τους και στα υγειονομικά χαρακτηριστικά το βαθμό ασφάλειας της υγείας των εμπλεκόμενων μερών, αυτών που διαμένουν καθώς και αυτών που εργάζονται για την μεταφορά και την εγκατάστασή τους. Τα μονωτικά υλικά χρησιμοποιούνται αφενός μεν σε νεόδμητα παθητικά κτίρια και αφετέρου σε ανακαίνιση συμβατικών κτιρίων με σκοπό να μετατραπούν σε παθητικά. Η ανέγερση νεόδμητων παθητικών κτιρίων καθώς και η ανακαίνηση συμβατικών για την μετατροπή τους σε παθητικά θα πρέπει να συμμορφώνεται με τα κριτήρια που διέπουν τα παθητικά κτίρια. Τα κριτήρια αυτά σχετίζονται με τις απαιτήσεις θερμομόνωσης, αεροστεγανότητας, συστήματος εξαερισμού και παθητικής χρήσης της ηλιακής ενέργειας του κτιρίου. Για τον τρόπο μετατροπής συμβατικών κτιρίων σε παθητικά, καθορίστηκαν δύο διαφορετικά σενάρια συμβατικών ήδη αναγερθέντων κτιρίων και υποδείχτηκαν λύσεις για το κάθε κτίριο με τις οποίες εύκολα θα μπορούσαν να μετατραπούν σε παθητικά. ΕΙΣΑΓΩΓΗ Η θερμομόνωση επιδρά θετικά στο εσωκλίµα, διότι βοηθάει στην διατήρηση ομοιόμορφης κατανοµής της θερμοκρασίας σε όλο το κτίριο. Οι τοίχοι, οι οροφές και τα πατώµατα καθίστανται θερµότερα κατά την περίοδο θέρµανσης και ψυχρότερα κατά την περίοδο δροσισµού. Η θερμομόνωση επιτυγχάνεται με χρήση θερμομονωτικών υλικών. Τα θερμομονωτικά υλικά είναι διαφόρων τύπων όπως οργανικά, ανόργανα, σύνθετα και νέας τεχνολογίας και χαρακτηρίζονται από διάφορα χαρακτηριστικά όπως τεχνικά, περιβαλλοντικά και υγειονομικά. Κατά την επιλογή ενός μονωτικού υλικού υπεισέρχεται και ο παράγοντας κόστους. Συχνά, λοιπόν, παρατηρείται ότι είναι πολύ δύσκολη η βέλτιστη επιλογή μονωτικού υλικού ώστε να ικανοποιούνται, σε αποδεκτά όρια, τα προαναφερθέντα χαρακτηριστικά και ταυτόχρονα το κόστος τους να παραμένει χαμηλό. Έτσι, για παράδειγμα σε τεχνικό επίπεδο, ανάλογα με τις κλιματολογικές συνθήκες του κάθε τόπου δημιουργούνται άλλες ανάγκες για θερμομόνωση, και συνεπώς και άλλη ποσότητα αλλά και τύπο μονωτικού υλικού. Επίσης, σε περιβαντολλογικό επίπεδο, δημιουργούνται άλλες ανάγκες για την προστασία του περιβάλλοντος και σε υγειονομικό επίπεδο, δημιουργούνται διαφορετικές ανάγκες για το βαθμό διασφάλισης της υγείας. Προφανώς, η χρήση μονωτικών

Ballistic design and testing of a composite armour reinforced by CNTs suitable for armoured vehicles, Apr 26, 2023

Tsirogiannis, E.C.; Siasos, G.I.; Stavroulakis, G.E.; Makridis, S.S. Lightweight Design and Welding Manufacturing of a Hydrogen Fuel Cell Powered Car’s Chassis. Challenges 2018, 9, 25, May 27, 2018